There are already enough mosquitoes in Ohio, but Ohio State’s biochemistry department raises them to find better ways to kill the ones carrying tropical diseases such as malaria.

The biochemistry department is working with a major type of organic pesticide to develop mutations that will kill different mosquito species in North America.

The pesticide is a bacterium called Bacillus thuringiensis (Bt). It is a commercially available biological pesticide.

Researchers have isolated a single protein named Cry4Ba in the Bt that helps the bacterium do its job. They mutated the protein into different forms so it would target specific species of mosquitoes.

The type of Bt the biochemistry department is using is targeted towards mosquito larvae, said Donald H. Dean, director and chair of the graduate studies committee of the biochemistry department.

Dean has been overseeing the Bt mutation on mosquitoes research at OSU since it began six years ago.

“Bt is one of the few natural pesticides allowable for organic farming,” said Autumn White, a senior in biochemistry. “It was first discovered in 1901 as an organism causing disease in silkworms.”

Commercial Bt is normally applied to leaves or other environments where insect larvae will ingest it. It is used worldwide for the control of plant eating insects in their early stages such as caterpillars and mosquitoes.

The department tests the variants of the Cry4Ba protein with four species of mosquito larvae by feeding them the Bt and recording how many are killed off.

“The mosquitoes can only be killed with Bt in their larvae stages. Short of swatting them, you really can’t kill the adults,” White said.

Dean said the mosquitoes chosen for the research are the best-known species and major carriers of diseases such as malaria and West Nile virus.

The Bt in its original form kills off mosquitoes having the potential to carry malaria and yellow fever.

Dr. Mohd Amir F. Abdullah was the first researcher at OSU to mutate the Bt so it would target new mosquito species, specifically the major carriers of West Nile virus.

“We knew what genes to target from past research, and we mutated them using genetic engineering,” Abdullah said.

White mutated the protein to a different form that is more efficient in killing the major carrier of malaria.

“The goal is to find the mutation of Cry4Ba which will kill the most larvae using the least amount of pesticide,” White said.

The mosquitoes are raised in an environment-controlled room and grown into different stages of larvae.

White said the mosquitoes do not carry any viruses because they are bred in a sterile environment, but they have the potential to contract diseases and spread them.

Dean and his department have been working with various groups at OSU to apply their research to the outside environment. Richard T. Sayre, professor and chairman of the Department of Plant Biology, is heading up one group that plans to introduce the mutations of Bt to green algae that mosquito larvae eat.

There will be testing done first to make sure new mutations of Bt are safe for human contact, Dean said. The form of Bt used world wide has no effect on humans and can even be put in drinking water.

Dean said the results of Bt mutation research are beneficial because it is always good to have many types of pesticides to address the problems of mosquitoes developing resistance.

“One could say mosquitoes are the most dangerous animals on the earth because they can kill more people than any other animal,” Dean said.